If you’ve just upgraded to OS X 10.9 “Mavericks”, but chose to stay with good ol’ Xcode 4.6.3, it may stall at “Creating universal binary” when building projects.
If it happened to you, check if
lipo command works on your system. If it does not, get lipo from Xcode 5 distro, like so:
sudo cp /Volumes/Xcode/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/lipo /usr/bin